Service-Specific Forwarding in LDP-RSVP Hybrid Networks
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Solution Overview
Problem
Existing network technologies face challenges in efficiently directing different types of data traffic, such as voice and data, with varying requirements, through a multi-service Multiprotocol Label Switching (MPLS) network, especially when these traffic types have the same Quality of Service (QoS) class and cannot be differentiated using EXP bits or other forwarding-plane markings.
Innovation Solution
The solution involves using control-plane information to select core RSVP LSPs for carrying LDP LSP traffic, where core routers dynamically construct forwarding state to route different types of data traffic along appropriate paths by advertising label map messages with unique identifiers and configuring policies on routers to associate specific data traffic with distinct LSPs, allowing for traffic separation without relying on EXP bit markings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If LDP LSPs are used to carry traffic in an LDP-RSVP hybrid network, then traffic engineering flexibility is reduced, but network simplicity is improved
Solution Approach 1:
The patent introduces an intermediary mechanism where LDP label map messages carry service-specific identifiers that act as mediators between LDP LSPs and RSVP LSPs. This allows LDP LSPs to indirectly access traffic engineering capabilities of RSVP LSPs through the intermediary of service identifiers, resolving the contradiction by maintaining LDP simplicity while enabling RSVP-level traffic engineering flexibility.
Solution Approach 2:
The patent segments the traffic identification function by separating service-specific identifiers from QoS markings. Instead of relying solely on EXP bits, the system uses distinct service identifiers in LDP label map messages to segment and categorize different traffic types (voice, data, video), enabling fine-grained traffic engineering while maintaining overall network simplicity.
2Device complexity
If EXP bits are used to differentiate traffic types, then forwarding plane complexity is reduced, but traffic differentiation capability is insufficient
Solution Approach 1:
The patent adds another dimension to traffic differentiation by introducing service-specific identifiers in the control plane (LDP label map messages) beyond the traditional EXP bits in the forwarding plane. This dimensional extension allows rich traffic differentiation capability while keeping the forwarding plane simple, as the additional identification layer operates in the control plane dimension.
Solution Approach 2:
The patent applies preliminary action by pre-configuring service-specific identifiers and their associated RSVP LSP mappings in the control plane before traffic arrives. This preliminary configuration enables the forwarding plane to simply match packets to pre-established mappings without complex real-time differentiation, resolving the contradiction between simplicity and capability.
3Difficulty of detecting and measuring
If service-specific identifiers are added to LDP label map messages, then traffic differentiation capability is improved, but control plane complexity increases
Solution Approach 1:
The patent makes the LDP label map message structure universal by extending it to carry service-specific identifiers that can represent multiple traffic types (voice, data, video, etc.). This single extended message format serves multiple functions: traditional label distribution, service identification, and traffic engineering signaling, improving differentiation capability without proportionally increasing control plane complexity.
Solution Approach 2:
The patent applies parameter changes by modifying the LDP label map message to include additional service identifier parameters. These parameter additions enable fine-grained traffic differentiation while leveraging the existing LDP protocol framework, thus improving capability with controlled complexity increase rather than requiring a completely new protocol.
4Adaptability or versatility
If RSVP LSPs are established for all traffic types, then traffic engineering capability is improved, but network resource consumption increases
Solution Approach 1:
The patent applies partial action by establishing RSVP LSPs only for specific service types that require traffic engineering (such as voice and video), rather than for all traffic types. LDP LSPs continue to handle traffic types that do not require sophisticated engineering. This selective approach improves traffic engineering capability where needed while conserving network resources by avoiding unnecessary RSVP LSP establishment for all traffic.
Data Source
AI summary
A router receives a control plane message for constructing a first LSP to a destination within a network that conforms to a first type of LSP. The control plane message includes a label for the first LSP and an identifier that identifies a first type of data traffic. The router receives a second control plane message for constructing a second LSP that conforms to the first type of LSP. The second control plane message includes a label for the second LSP and an identifier that identifies a second type of data traffic. The router installs forwarding state in accordance with policies that associate the first and second types of data traffic with different LSPs of a second type that each traverse different paths through the network, and forwards packets via the interface in accordance with the installed forwarding state.